Method and apparatus for identifying an instrument location based on measuring a characteristic

ABSTRACT

A method to determine the location of an instrument within a patient can be based upon the measuring of a characteristic within the patient and matching the currently measured characteristic with a previously measured characteristic. If the measurements of a characteristic matches in an appropriate or selected manner then a location match can be determined. The characteristic can be any appropriate characteristic and measured in any appropriate way.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/465,050 filed on May 13, 2009. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present application relates to a method and apparatus of identifyinga location of an instrument relative to a patient, and particularly toidentifying a location of an instrument relative to a patient based uponmeasurements taken at the position of the instrument.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

A procedure can be performed on a patient using various techniques andinstrumentation. For example, ablation or stent implantation can beperformed relative to a particular and selected portion of a patient'sheart. Various techniques are required to determine a location of aninstrument prior to performing a particular procedure.

For example, it is generally selected to substantially precisely locatethe ablation instrument to ensure appropriate ablation of an appropriateportion of the anatomy. X-ray images may be acquired to determine thelocation of an instrument in a patient prior to performing an ablationprocedure. Arrhythmias of a patient's heart can be treated with anablation of a particular and specific anatomical location within apatient's heart. Generally, the selected results, such as an eliminationof an arrhythmia, are achieved only when the particular anatomicallocation is ablated.

Determining the location of the instrument can also be performed withgenerally known navigation instruments and procedures. The navigationinstrument and procedures, however, may also require additionalequipment and specialized training. The navigated instruments mayrequire additional capital equipment and greater size. Alternatively, aprocedure may be done in an open manner. Thus, navigation or positiondetermination is done by the surgeon through direct visualization. Openprocedures, however, may be more traumatic to patients.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A method to determine the location of an instrument within a patient canbe based upon the acquisition and measuring of specific characteristicswithin the patient. The characteristic can be a feature orcharacteristic that is extracted from a data. For example, trainingmeasurements can be made of a patient or population of patients at aspecific location within the patient. A specific location can include,as an example, a superior vena cava junction into the right atrium.Measurements of characteristics can lead to acquisition of informationof a patient or population of patients regarding the specific location.Characteristics can include motion or movement, pressure, pulsativepressure, electrograms, or other information. The acquired traininginformation can then be used to create a database that can be accessedto identify when the location is reached by an instrument based uponmatching pre-acquired characteristic measurements with current orprocedure measurements of the characteristics. The pre-acquiredcharacteristic can be used to generate a training or pre-acquiredfingerprint and the procedure measurements can be used to generate aprocedure fingerprint. An algorithm or system can determine theprobability of a match between the training fingerprint and theprocedure fingerprint.

According to various embodiments, a method of locating an instrument caninclude a training phase and a procedure phase. The training phase caninclude selecting a training location; identifying a characteristic atthe training location; acquiring a training datum by measuring thecharacteristic at the training location in a training instance; anddetermining a pattern in the training datum at the training location.The procedure phase can follow the training phase and include acquiringa procedure datum by measuring the characteristic during a procedure ata procedure location; and determining if the procedure datum matches thedetermined pattern.

According to various embodiments a method of locating an instrument caninclude a training phase. The training phase can include selecting atraining location; selecting a characteristic at the training location;obtaining a set of characteristic training data by measuring thecharacteristic at the training location in a training instance;determining a pattern in the training data at the training location; andsaving the determined pattern as a predetermined pattern. A procedure orintervention may use the predetermined pattern to identify a location ofan instrument.

According to various embodiments a system of locating an instrument caninclude an input instrument operable to be positioned into an anatomy toinput data to the memory system. A first classifier can classify theinput data into a classification from the input instrument and aprocessor can determine a location of the input instrument based uponthe classification of the input data. An output can be made to outputthe location to a user.

The information can be acquired with an instrument positioned within apatient, such as a catheter. Other techniques can also be used toacquire the information of the characteristics within the patient. Forexample, image data can be used to acquire characteristic information ata particular location of the patient. Magnetic Resonance Image (MRI) orcomputer tomography (CT) data can be used to determine certain specificcharacteristic information that can then be used to determine measurabledata, such as characteristics measured with an instrument. For example,image data can be analyzed to determine a pulsative pressure, heartwall, or organ motion at a specific location.

Instruments can then be used to make procedure or current measurementsof the characteristics. According to various embodiments a catheter caninclude a motion sensor (e.g. an accelerometer) for measuring motion ofa portion of a patient. According to various embodiments, a catheter caninclude a pressure sensor that measures pressure as it is moved orpositioned within a patient. As the pressure is measured, such as apulsative pressure, the measured pulsative pressure can be compared tothe database of pulsative pressures to identify when the catheter ispositioned at a specific physical location within the patient based uponmatching the pulsative pressure currently measured and that within thedatabase. It will be understood that any appropriate comparison can beused to determine if a match is found.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a flowchart of a procedure, according to various embodiments;

FIG. 2A-C are flowcharts of a training process, according to variousembodiments;

FIG. 3 is a flowchart or a procedure process, according to variousembodiments; and

FIG. 4 is a schematic environmental view of a position identificationsystem, according to various embodiments.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. It will be understood that although thefollowing description may relate specifically to an identifiedcharacteristic within a heart of the patient, that the method andinstrumentation disclosed herein can be used in any appropriate locationwithin the patient. For example, instruments can be positioned within aheart, a liver, a pulmonary region, a neurological region, or otherappropriate portions of the patient. Accordingly, the descriptionrelating to a cardiac procedure herein is merely exemplary and notintended to limit the scope of the current disclosure or the includedclaims.

With reference to FIG. 1, a system or process 10 is illustrated in aflow chart. The system 10 can include in start block 12. After startblock 12, a training phase can occur in block 14. The training phase, asdiscussed further herein, generally relates to making trainingmeasurements to acquire information or data of a characteristic at aspecific location. The information can be used to train a computersystem, neural network, and/or algorithm or for creating a databasebased upon the acquired characteristic information. Following thetraining phase, a procedure phase in block 16 can occur. The procedurephase in block 16 can include performing a procedure on a patient basedat least in part upon the training phase in block 14. After theprocedure, the system 10 can end in end block 18.

It will be understood, the system 10, including the training phase inblock 14 and the procedure phase in block 16, need not occursequentially at a given time. For example, the training phase in block14 can occur using a plurality of patients or over an extended period oftime to train a system (such as a classifier) or generate a database.The training phase in block 14 can occur at any appropriate time togenerate an appropriately trained system. The procedure phase in block16, therefore, can occur at any appropriate time after the trainingphase in block 14.

In addition, it will be understood that the training phase in block 14is not always required to proceed to the procedure phase in block 16.For example, once the training phase in block 14 is completed and adatabase or other appropriate system has been taught or created theprocedure can proceed any number of times. Thus, to perform a procedureaccording to the procedure phase in block 16, a training phase in block14 need not always immediately proceed the procedure phase in block 16.

As discussed further herein, the training phase in block 14 can includethe acquisition of training data relating to a population of patients.Accordingly, the data can be statistically analyzed or classified in thetraining phase in block 14. The training phase in block 14 can alsoinclude generating a fingerprint or pattern based upon the acquiredinformation. The fingerprint can be imbedded in a classification systemthat can include feature extraction to allow for classification of aprocedure datum acquired with a procedure measurement during aprocedure. After this occurs, the procedure phase in block 16 can beperformed using the fingerprint from the training system in block 14.

The training phase in block 14 can occur based upon a particularpatient, such as the patient upon which the procedure in block 16 isperformed. Accordingly, the training phase in block 14 can becontemporaneous or close in time to the procedure phase in block 16.Therefore, one skilled in the art will understand the training phase inblock 14 can occur at any appropriate time relative to the procedurephase in block 16.

With initial reference to FIG. 2A, the training phase 14 is illustratedin greater detail. The training phase in block 14 can include aplurality of steps or sub-procedures to appropriately train a system orgenerate a database or fingerprint. The fingerprint that is generatedcan be a single datum or a series of data or pattern that is generated.The pattern can be stored in a database or a plurality of fingerprintscan be stored in a database. Alternatively, a single file or accessiblememory portion can be used to store the fingerprint rather than adatabase.

The training phase 14 can begin in start block 20. After starting thetraining process, a specific location can be selected in block 22. Thespecific location can be any appropriate location in a patient or anyother appropriate position. The location can be specifically known ordetermined with imaging navigation, or other location identificationtechniques. Data acquisition, such as acquiring information regarding aspecific location, can occur in block 30. As discussed further herein,various data acquisition techniques can be used to acquire the locationspecific information. The location specific information can be atlocations within any appropriate portion of an anatomy. For example, thelocation of specific information can be within a heart, brain,vasculature, pulmonary system, or any appropriate specific location. Thespecific location, as discussed further herein, can include the locationof the superior of vena cava juncture with the right atrium. Inaddition, as also discussed further herein, the type of data acquired inthe training data acquisition in block 30 can be any appropriate data.As a brief example, appropriate data can include electrograms, pulsativepressures, acceleration, velocity, static or dynamic position, or otherselected data.

After the training data is acquired in block 30, the data can be savedin block 40. Saving the data in block 40 can be any appropriate savingprocedure. For example, the data can be saved to a network memorysystem, a volatile memory, a non-volatile memory, or any appropriatememory. Regardless, the acquired information in block 30 can be saved inblock 40. Additionally, the data saved in block 40 can be accessed forvarious procedures.

The data that is saved in block 40 can simply be added to previouslyacquired data or used to replace the previously acquired data. Forexample, in a series of patients each patient can be used to acquiredata and all of the data can be saved. Alternatively, a series of datagathering procedures can be performed on a single patient or group ofpatients. It can be selected to only save a portion of the acquireddata.

After the data is acquired in block 30 and saved in block 40,determining a fingerprint for the location can occur in block 50. Asdiscussed above, the data acquired is for a specific location.Therefore, the data acquired in block 30 regarding the specific locationcan be used to generate or determine a fingerprint, also referred to asa training fingerprint, for the specific location selected in block 22.The fingerprint, as further discussed herein, can then be compared tofeatures or characteristics measured during a procedure. The proceduremeasurements can be compared to the fingerprint generated from thetraining data. Thus, the procedure measurements can be referred to as aprocedure fingerprint. A program or algorithm, such as a neural networkdiscussed herein, can compare the training fingerprint to the proceduremeasurements or fingerprint.

The determination of the fingerprint or the fingerprint can be anyappropriate determination. Determining the fingerprint can involvestatistical based analysis, neural networks, or probabilistic basedmodels. As discussed herein, the fingerprint can include a model orpattern that is found or determined based upon an analysis using analgorithm or with other types of review. Also, the fingerprint can beidentified by executing an algorithm by a processor or with manualdetermination, or a combination of both automatic and manualdetermination. For example, a fingerprint can include a probablepulsative pressure or electrogram that is present at the SVC junction.The probabilistic pulsative pressure can be based on measurements of onepatient or of a plurality of patients. If the pulsative pressureacquired in block 30 is based upon a population of patients, a variationwithin the population of patients can be accounted for when determiningthe fingerprint in block 50.

The data acquired in block 30 can be analyzed according to appropriatetechniques, such as those disclosed in Duda et al., PatternClassification, 2^(nd) Ed., John Wiley & Sons, 2001; and Theodoridis etal., Pattern Recognition, 3^(rd) Ed., Elsevier, 2006; Introduction tothe Theory of Neural Computation, Hertz, John A., et al., WestviewPress, 1991; all incorporated herein by reference. The analytical,computational, and combinative techniques can be used to identifyrelationships amongst the acquired and saved data, from blocks 30 and40, to determine the fingerprint in block 50 and/or compare newlyacquired data with a fingerprint to determine a match or a probabilityof a match. In addition, it will be understood, that a manual analysiscan be used to determine a fingerprint of the saved data in block 40.The techniques can include identifying features in the data that can beused to classify later acquired data.

The fingerprint can be used with any appropriate system, such as aneural network or statistical analysis system or algorithm to find amatch to or a probability of a match to a later measuredcharacteristics. The characteristic can also be referred to as a featurethat is present in a set of data, such as training data. Thefingerprint, generated from the feature, can be manually generated,automatically generated, or generated based on a combination ofautomatic and manual inputs. The fingerprint can also be referred to asan input into the system or algorithm that is to determine a match withthe later measured characteristic.

The fingerprint may include only one feature or more than one feature.If more than one feature is included in the fingerprint, the featuresmay be blended into a single fingerprint or left as separate featureswithin the fingerprint. If the fingerprint is a blended fingerprint itmay include averaged data or data that is manipulated over time. If thefeatures are left separate the features can be saved and accessed asdistinct and separate points with or without relation to time or otherdynamic measurements.

An example of a blend of multiple features in the fingerprint mayinclude a measured position (but may also include a pulsative pressure,velocity, etc.) during a physiological cycle, such as a cardiac cycle.The measured position can be blended with the cardiac cycle to generatea blended curve indicating the change in position over the time of thecardiac cycle. Also, the curve could be based on an average of severalcardiac cycles and several subjects, as discussed herein. The blendedcurve could then be matched to a patient or procedure curve.

When the features are selected to be separate, the measured positioncould be measured or determined at distinct points in the cardiac cycle.The measured positions can be averaged over several cardiac cyclesand/or population, as discussed herein. Each of the measured points andtheir relation to the cardiac cycle could be used to compare to aprocedure measurement. Thus, rather than a curve or blend of theposition and the cardiac cycle, the two are kept separate for generationof the fingerprint.

It will also be understood that the use of the phrase “fingerprint” isnot intended to limit or identify an identity in the data. The phrase orterm fingerprint is merely understood to identify a model or featurethat is used as an input for the classification system that can becompared to procedure measured characteristic data in the procedurephase 16. It will be understood that fingerprint used herein, unlessspecified otherwise, does not relate to a literal print left by afinger. Rather, fingerprint is directed to a pattern that is generatedor recognized from the acquired data.

Once the fingerprint has been determined in block 50, it can be saved ina database in block 60. The saving of the fingerprint in a database canbe any appropriate saving procedure, similar to the saving of the datain block 40. Also, a database need not be created, but only a file in anaccessible data format. It will be understood, however, that thedatabase may be accessed for various procedures, such as during theprocedure phase 16. In addition, various instruments can be used tocollect or measure data relating to a patient during the procedure phasein block 16, which can be interconnected with a processor and/orclassifier system. The processor system can access the database intowhich the fingerprint is saved in block 60 for analysis in determinationof the match to a fingerprint, as discussed further herein. Theprocessor system may also be a classifier system or algorithm operableto classify incoming data based upon the fingerprint, also theclassifier may be a single or separate system. The training phase canthen end in block 70.

With reference to FIG. 2B, exemplary data acquisition or techniques isillustrated in block 30 a. The exemplary data acquisition in block 30 acan be used to acquire data in block 30, in FIG. 2A. Data acquisitioncan be data acquired from any appropriate selected source. For example,data can be acquired through an invasive procedure. Summarized in block30 a, a catheter can be navigated to a location within one or morepatients.

A catheter can be navigated within the patient to acquire informationregarding the one or more patients to acquire the data for block 30 ofthe training process 14. According to various embodiments, an invasiveprocedure, as noted in block 30 a, can include moving a catheterwithin 1) patients in a population of patients or 2) within a singlepatient. If the catheter is moved relative to a population of patients,a set of data points can be acquired for each patient which can includea plurality of data points. This allows multiple sets of data pointsregarding each of the patients to be acquired. All of these data pointscan be saved for determining a fingerprint in block 50. The data caninclude any appropriate data, such as that discussed below, for one ormany locations within each patient of the population. A study group ofpatients can be interrogated with the catheter, or other appropriateinvasive instrument, to measure the characteristic and acquire traininginformation at one or more locations within each patient in thepopulation.

The training information can then be saved and used to determine afingerprint without any patient identifying information being acquiredand saved with the saved acquired information, unless selected, asdiscussed below. For example, a pulsative pressure can be measured at aselected point within the patient. That particular pulsative pressure,either one or multiple pressures at one point, can be saved or averaged.A pulsative pressure at the same location, either a single or averagepulsative pressure from each of the patients in the population can alsobe acquired and saved. This information need not be associated with anyother information regarding the patient, such as name, age, otherconditions, or the like. Even if other information is acquired, it maybe simply to clarify or provide additional information for thefingerprint created in block 50.

The information can, however, also be associated with specific patientinformation. For example, if a pulsative pressure is taken in a patientwith an atrial fibrillation, that information can be associated with thepulsative pressure measured in the patient of the population. Inaddition, a separate database or fingerprint can be created for patientswith particular conditions. For example, electrograms of a populationwith atrial fibrillation or with a heart attack can be generated tocreate illness specific fingerprints. Thus, patient specific informationcan also be used to help generated or identify the fingerprint. Thisinformation can also be population specific, as opposed to individualspecific. For example, a population of individuals having had at leastone infarction can be used to generated a database or fingerprint.

It may also be selected to acquire information regarding a singlepatient. For example, during an invasive procedure, such as an initialprocedure, information can be acquired of the patient, includingpulsative pressures, electrograms, or the like. During a subsequentprocedure, this information can be used regarding the same specificpatient. For example, during implantation of a stent in a vasculature ofa patient, information can be acquired of that patient and a fingerprintdetermined. During a second procedure, such as the positioning of asecond stent or a angioplasty, the patient specific fingerprint can beused, as discussed further herein, to identify the location of acatheter during the second procedure. Therefore, rather than requiringan invasive procedure on more than one patient, information regarding asingle patient can be used to identify the same specific locationswithin the patient, according to various embodiments.

Whether acquired in a single patient or a population, the informationacquired in block 30 a can be any appropriate information. It can bedirectly measured or inferred from the instrument positioned within thepatient during the invasive procedure noted in A). The informationacquired in B) in block 30 a can be any appropriate informationregarding a characteristic. For example, i) instrument motion caninclude acceleration, velocity, position, or other information. Forexample, a position identification or tracking portion, such as thosedisclosed in U.S. Pat. App. Pub. No. 2004/0097805 (U.S. patentapplication Ser. No. 10/619,216) entitled, “NAVIGATION SYSTEM FORCARDIAC THERAPIES” including an electromagnetic navigation or trackingsystem and U.S. Pat. App. Pub. No. 2009/0264752 (U.S. patent applicationSer. No. 12/117,537) entitled, “METHOD AND APPARATUS FOR MAPPING ASTRUCTURE”, including the navigation or mapping system such anelectrical potential system, both incorporated herein by reference, canbe associated with the instrument to determine acceleration or velocityof the instrument by measuring displacement of the instrument over time.

When an instrument is positioned within a superior vena cava, velocityof the instrument moving within the superior vena cava can be measured.Also, the information can be generated relating to various patientrhythms or cycles. For example, motion during different and specificportions of the cardiac cycle can be measured. The motion at differentparts of the cycle can also be used to generate the fingerprint. Thus, afingerprint, as discussed herein, can include more than one type ofinformation. According to various embodiments it can include motion at aspecific time in a cardiac cycle. Though motion at a specific time in arespiration cycle or other cycles can be used. This information can beacquired and saved in block 40.

Additional or alternative characteristics about which information isacquired can be ii) fluid motion. Fluid motion can be motion measured ofthe fluid such as the direction, turbulence, velocity or other fluidmotion information. Sensors on the instrument being positioned withinthe patient can measure the fluid motion relative to the instrument. Theinformation regarding the fluid motion can be saved in block 40.

Additional or alternative information can be acquired regarding thecharacteristic of iii) electrical activity. Electrical activity caninclude electrical activity that is measured with various portions, suchas an electrode on the instrument. Information can be acquired aboutelectrograms, electrophysiology, comparative electrophysiology, or otherelectrical activity information. For example, the instrument can includean electrode that can measure a potential that is generated within amuscle or tissue and this data can be saved in block 40.

Additional or alternative characteristics can include (iv) pressureinformation. Pressure information can include fluid pressure, tissuepressure, pulsative pressure, or other pressure measurements. Forexample, pressure of a fluid on the instrument can be measured with anappropriate instrument. These instruments can include a bladder orballoon can be inflated with a non-compressible material and pressure onthis balloon can be measured with an appropriate pressure meter.Pulsative pressure can include instantaneous pressure changes measuredon the balloon within the patient. Again, the data regarding pressurecan be saved in block 40.

Further or additional alternative characteristics can include (v) tissuestiffness or density. For example, a pressure sensor can be associatedwith a catheter and the catheter can be pressed into tissue to acquireinformation regarding the stiffness. Also, an ultrasound (e.g.ultrasound catheter) can be used to determine or estimate tissuestiffness.

The information acquired in (B) can be any appropriate information andneed not be limited to the exemplary types of information listed inblock 30 a. Various sensors that might be incorporated or associatedwith a catheter or other invasive instruments can be used to acquire anyinformation regarding a characteristic at a particular location withinthe patient. Nevertheless, as the information is acquired, a position ofthe instrument is also known relative to the patient, including or atthe specific location for which the fingerprint is being developed. Theposition of the instrument can be determined via a position sensor onthe catheter or associated with the catheter, imaging of the patient andthe instrument, or any other appropriate or known location ordetermination technique or procedure. For example, a position sensor canbe associated with the catheter as it is positioned within a patient ofthe population or a single patient, as discussed above. The traininginformation about the characteristic can then be acquired and associatedwith the known position of the catheter within the patient. When savingthe training data within block 40, it can then include both a knownlocation of the instrument and the acquired training information that ismeasured with the instrument. Accordingly, the data saved in block 40that is used to determine the fingerprint in block 50 can include bothknown locations and the acquired information. As discussed furtherherein, the acquired information and the known location of the acquiredinformation can be used to create a fingerprint for various purposes.

Turning to FIG. 2C and block 30 b, the acquisition of traininginformation in block 30 of the training process 14 can includenon-invasive acquisition techniques. For example, information can beacquired or produced from various imaging techniques, including (i) CT,(ii) MRI, (iii) ultrasound (US), (iv) fluoroscopy, or other appropriateimaging techniques. Additionally, non-invasive information can beacquired via external sensing devices, such as an electro-cardiogramdevice. The non-invasive training information can be acquired again,from a 1) population of patients or 2) single patient. The population ofpatients can be any appropriate population of patients that is subjectedto an interrogation by non-invasive information gathering techniques.Further, the single patient can be a single patient on which a procedureis to be performed and the non-invasive techniques can be used tointerrogate the single patient. Regardless of whether a population ofpatients or a single patient is used to acquire in the traininginformation, the information can be saved in block 40. As discussedabove, in relation to the information acquisition in block 30, theinformation can be gathered as individual points, averaged, associatedor not associated with any other patient information, or any appropriatedata acquisition model.

Regardless of whether a single patient or population of patients is usedto acquire the data, the non-invasive information can be analyzed for aparticular or multiple particular measurements to define or obtain theinformation (B) about a characteristic. As discussed above, theinformation that is acquired can be any appropriate information, and caninclude (i) instrument motion, (ii) fluid motion, (iii) electricalactivity, (iv) pressure, (v) tissue stiffness or density, or any otherappropriate information. The information that is acquired from thenon-invasive interrogation technique can be the same or differentinformation from that acquired with the instrument in block 30 a.Regardless, the information that is obtained through the analysis of thenon-invasive information or interrogation technique can be known byanalysis of the non-invasive information. For example, a dopplerultrasound (US) can be used to measure fluid motion. The location of thefluid motion is known due to its relative position to the anatomy in theimaging data. Other non-invasive information techniques can alsoidentify the location for which the information is obtained.

Regardless of the procedure for the acquiring the training data in block30, the data can be saved in block 40, as illustrated in FIG. 2. Afingerprint can then be determined for the specific location and thefingerprint can be saved in the database, as also illustrated in thetraining process in FIG. 2. Once the fingerprint is saved in thedatabase, or any other appropriate accessible system, the fingerprintcan be used during the procedure 16, illustrated in detail in FIG. 3.Briefly, because the fingerprint relates to a specific and knownlocation within a subject, such as a patient or system, making aprocedure measurement that matches the saved or predeterminedfingerprint can be used to determine the location at which the proceduremeasurement is made. An instrument can make a procedure measurement of acharacteristic in the patient and the procedure measurement can beanalyzed to determine a match to the saved fingerprint. In other words,during the training process location of an instrument was known and thefingerprint was determined based upon the data acquired at thatlocation. Matching a procedure measurement to a fingerprint allows thedetermination that the measurement is made at the same location as itwas during the training procedure. The determination can be madeautomatically, such as with a processor, or manually, by a user.

The procedure 16 can be followed to perform a procedure relative to anyportion of a patient, such as within or near the heart of the patient, abrain of the patient, a vasculature of the patient, or any otherappropriate portion. The procedure performed in procedure block 16 caninclude both making a measurement to be matched to the fingerprint andperforming a further selected intervention or procedure at a selectedlocation. For example, a stent can be implanted, an ablation can beperformed, a lead can be implanted, and other appropriate proceduresperformed. It will be understood, that the procedure 16 can be used toidentify the location of an instrument at any appropriate location forwhich a fingerprint has been predetermined and any appropriate procedurecan then be carried out.

In addition, it will be understood that the training procedure 14 inFIG. 2A and the procedure 16 in FIG. 3 can be used for any appropriatenon-surgical or non-medical procedure. For example, the training process14 in FIG. 2A can be used to identify a fingerprint for a particularlocation in any of selected dynamic or static system. In a mechanicalsystem an exploratory tool or manipulative tool can be moved within acasing to acquire or measure information regarding portions of themechanical system within the casing. The measurements or information canbe used to identify specific locations within the casing and thisinformation can be used to determine whether or not the manipulativetool is positioned at an appropriate location for performing a procedureon the mechanical system. The techniques could be used to identifypositions for servicing a mechanical system, positions for assembling orfabricating a mechanical system or any other appropriate procedure. As aspecific example, while building an airframe or a wing assembly for anairframe, small constrained places may later need to be threaded withelectrical wiring, insulated, welded, riveted, etc. A locationidentification system can be used to identify whether an instrument isat an appropriate location for performing a procedure, such as welding,riveting or the like.

The procedure 16 can begin at the start block 110. The start block caninclude, for example, forming an incision in a patient, moving aninstrument relative to a portion of the patient, or appropriate system,forming a burr hole in a patient, or any other appropriate startingprocedures. It will be further understood, that although the followingdescription may be directed to a specific anatomical procedure that theprocedure 16 can be used in any appropriate situation or procedure, suchas for performing a procedure on a mechanical system.

After starting a procedure of block 110, measuring one or morecharacteristics with an instrument during the procedure 16 can occur inblock 112. Measuring the characteristic during a procedure can bemeasuring any appropriate characteristic, such as the characteristic forwhich training information was acquired in block 30 through anyappropriate technique, such as the techniques described in blocks 30 aand 30 b. The training information previously acquired regarding thecharacteristic can be similar to a procedure information of thecharacteristic taken in block 112. For example, an instrument positionedwithin a patient can be used to measure a pressure, such as a pulsativepressure, within the patient. The measurement of the characteristic caninclude a measurement of the pulsative pressure within the patient thatis similar to a pulsative pressure of the acquired data in block 30. Inother words, if pulsative pressure was the training information that wasused to determine the fingerprint the procedure information can bemeasuring a pulsative pressure as well. A determined match between theprocedure measured pulsative pressure and the fingerprint based on thetraining measurement can be used to identify a location of theinstrument making the procedure measurement.

Once one or more procedure measurements of a characteristic have beenmade, a program and/or algorithm can be executed with a processor tomatch the procedure measured characteristic with the fingerprint savedin block 60. As discussed above, the fingerprint can be any appropriatefingerprint and a comparison can be made based upon any appropriate ruleor via a classification. As discussed above, appropriate rules caninclude algorithms or computer programs that can be executed todetermine whether a match is found between the fingerprint and themeasured characteristic. For example, the pulsative pressurefingerprints can include a pulsative pressure or a pulsative or changein pressure over time or physiological cycle, such as anelectrocardiogram (ECG). During the execution of the program, theprogram can determine whether the procedure pulsative pressure measuredin block 112 is similar to the fingerprint saved in block 60. Thecomparison in block 114 can include an appropriate comparison includinga Bayesian classifier or a linear discrimination. It will be understood,therefore, that comparing the measured characteristic need not onlyinclude determining whether an exact match has been made between themeasured characteristic and the fingerprint or any of the particularsaved data in block 40. In fact, a comparison can determine whether thecharacteristic measured is close enough to the fingerprint to determineor identify a match. The comparison in block 114 can also determine acertainty of the match.

A decision block 116 includes determining whether a fingerprint matchhas been found. A fingerprint match may not be found and the NO routine118 may be followed to measure one or more characteristics at the sameor different location again. Again, the fingerprint generated and savedin the database in block 60 can be generated based upon appropriaterules. Accordingly, the fingerprint saved in the database in block 60may not be a single or discreet numerical value or measurement. It mayinclude a range or characteristic determination. Therefore, further oradditional measurements may be necessary to determine a match. Also, thefingerprint may be based on more than one type of measurement such aspressure and an electrogram.

In decision block 116, if a match to the fingerprint is found then theYES routine 120 can be followed to determine the location of theinstrument in an organ or portion of the patient based at least on thematch of fingerprint in block 122. As discussed above, the fingerprintis generated and based upon the acquisition of the data in a particularlocation within the patient, or other appropriate system such as amechanical system. Accordingly, a fingerprint of the characteristic,including pulsative pressures, tissue densities, fluid motion, or thelike, are related to a particular location within the patient.Accordingly, a pulsative pressure fingerprint X and the measuredpulsative pressure X′ are compared to one another. If an appropriaterelation or match is found it can be used to identify the location ofthe instrument, or at least a portion of the instrument acquiring themeasurement for a characteristic of block 112, within the patient.

Outputting the location of the instrument can be done in block 124. Thespecific location of the instrument can be within the heart, the brain,the vasculature, or any other appropriate location. For example, aparticular pulsative pressure or fluid motion can be used to generate afingerprint that is saved in database 60 for the superior vena cava, theOS between the right and left atriums, or other appropriate specificlocations within the patient. Accordingly, the specific location of theinstrument within the patient can be identified without an additionalinvasive procedure, additional navigational systems, imaging systems, orother systems in addition to the instrument that is in the patient andused to measure the characteristic of block 112.

Accordingly, a catheter that is positioned within the patient can beused to measure a pulsative pressure. That pulsative pressure can thenbe compared to a fingerprint. The fingerprint relates to a specificlocation so that when a match is found between the procedure measuredpulsative pressure in block 112 and the fingerprint, the location wherethe information for the fingerprint was acquired is used to identify thecurrent location of the instrument taking the procedure measurement inblock 112.

A catheter can be used to introduce a lead, an ablation device, or otherdevices relative to the patient. The identified location of the catheterthrough the procedure 16 can be used to insure an appropriatepositioning of the instrument during a procedure. Thus, a singlecatheter can be used for position identification and instrumentplacement.

After identifying and outputting the location, the procedure can end inblock 126. Ending the procedure at block 126 can include otherappropriate procedures, such as implanting a lead, performing anablation procedure or other procedures.

It will be understood that the execution of the program in block 114 andthe determination of the location of block 122 can be used to identifythe location of any appropriate instrument within a patient or any otherselected system. Further, positioning of the instrument can includepositioning an instrument in any appropriate portion of the patient ormechanical system. Additionally, it will be understood that the one ormore characteristics that are measured in block 112 can includemeasuring more than one characteristic at a particular location. Forexample, any two or more of a pulsative pressure, a motion (e.g. with anaccelerometer), and an electrogram can be measured at a selectedlocation in block 112. The multiple measured characteristics can then becompared to multiple different fingerprints to determine whether a matchis found in block 116. This can allow for confirmation or increasedpossibility of location determination of the position of the instrument.

When more than one characteristic is measured, then larger amount ofinformation can be used to make a location determination. For example,if two items (e.g. a motion fingerprint and a pulsative pressurefingerprint) are provided to identify a location, then the presence ofboth items can be used to identify the location. Thus, even if one itemis present, but the other is not, a positive identification can beavoided.

It will be further understood that the fingerprint determined in block50 and saved in block 60 can be a fingerprint that incorporates morethan one characteristic for the data acquired in block 30. For example,the fingerprint can include two or more of motion information, pulsativepressure information, ECG information, and electrogram information.Thus, the fingerprints determined in block 50, therefore, need not be afingerprint of a single characteristic that is measured at a particularlocation.

There can be two or more measurable characteristics at any specificlocation, such as within a superior vena cava, they can both be used todetermine the fingerprint in block 50. The two characteristics caninclude pulsative pressure and motion. The two can be combined into asingle finger print, such as a particular motion when a particularpulsative pressure is measured. Using multiple characteristics togenerate a single fingerprint can allow for the determination of aparticular or detailed fingerprint and for possibly more precise orcertain identification of a position of an instrument.

As discussed above, the fingerprint is part of an identification routinefor identifying a location of an instrument or device. When two or moremeasurements are taken they can be used to generate a procedurecharacteristic or procedure fingerprint. The procedure fingerprint canbe generated similar to the training fingerprint, but based only on themeasurement of the procedure location. When the procedure fingerprintincludes more than one characteristic it can be more precisely anduniquely determined. The same is true for the training fingerprint.Thus, a match of the training fingerprint and the procedure fingerprintcan be more difficult, but a match is more likely to a correct match andlocation identification.

Turning reference to FIG. 4, a patient 200 can have an instrument 202positioned relative to a selected portion of the patient 200, such as aheart or cardiac region 204. The instrument 202 can be any appropriateinstrument, such as a catheter 206 including a balloon or other portion208 that can measure a characteristic. A sensor, such as a temperaturesensor, can be positioned directly within the patient or, according tovarious embodiments, the balloon 208 can be used to amplify and transmita pressure, including a pulsative pressure, to a processor and/orclassifier system 210. The processor system 210 can include anyappropriate processor system, such as within a workstation or othercatheter control system. The instrument 202 can include a steerableportion, such that the catheter 206 can be a steerable catheter.Therefore, moving the catheter 206 through the patient 200 can be usedfor various procedures, such as implanting instruments or leads withinthe patient 200.

The processor system 210 can include human input portions, such as amouse and keyboard 212 and a display device 214. The display device 214can display various information regarding the measured characteristic inblock 112, the outputted location from block 124, and other appropriateinformation, such as a certainty of the determined outputted location.

As discussed above, it will be understood that any appropriatecharacteristic can be measured in block 112. Accordingly, the displaydevice 214 can include a measured characteristic indication 216. It willbe further understood that various portions, such as a graphical userinterface (GUI) can be used to alter, change, or add to the type ofmeasured characteristic. The one or more measured characteristics canthen be identified on the display device 214 in the display area 216.

The display device 214 can also include an instrument location output218. The location output 218 can be any appropriate output, such as aword output or graphical output. For example, the word “superior venacava” can be displayed on the display device 214 to identify thedetermined location of the instrument 206 within the patient 200. Inaddition, or alternative to the word output, a graphical illustration ofthe location of the instrument can also be displayed on the displaydevice 214. For example, a model or stylized illustration of a heart orvasculature and an icon representing the location of the instrument canbe displayed on the display device 214. In addition, or alternativelythereto, image data of the patient 200 can also be displayed on thedisplay device 214 and an icon representing the location of theinstrument 206 can be super-imposed on the display of the image data ofthe patient 200.

In addition, other information can be displayed regarding the procedure,such as the determination of the location of the instrument, in thepatient 200. For example, a certainty level or percentage 220 can beillustrated on the display device 214. The certainty can include acalculation of the amount or certainty of the match between theprocedure measured characteristic and the fingerprint.

A user, such as a surgeon, can base further or future actions based uponinformation outputted by the processor system 210. For example, thesurgeon can decide to alter the type or number of characteristics beingmeasured. Further, the surgeon can select to obtain more measurements ormeasure different types of characteristics to increase the certainty ofthe determined match. Regardless, the user can use the output on thedisplay device 214 to gain knowledge of the location of the instrument202 within the patient 200 after measuring a characteristic with theinstrument.

It will be understood that the processor system 210 can either be aseparate or single processor system with other processor systems. Forexample, the instrument 202 can be an ablation catheter or ablationsystem and the processor system 210 that executes the matching programin block 114 can be integrated into a control processor for the ablationinstrument or can be a separate processor system that either is incommunication with the ablation processor system or in communicationwith the instrument 202. Therefore, it will be understood, that thedetermination of the location of the instrument 202 can be used toassist in performing any appropriate procedure relative to the patient200 or in any other appropriate system.

The fingerprint can be based on more than one characteristic. Also, acharacteristic may be based on more than one type of measurement.Accordingly, a catheter or instrument can include more than onemeasuring sensor. Also, the fingerprint can be a rule defining whether ameasurement is within a rule to identify a location. In addition, thesystem for classifying or identifying a match can be an algorithm orexecutable program that embodies the algorithm for classifying theprocedure measurements.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

What is claimed is:
 1. A system of locating an instrument, comprising: afirst instrument having a sensor to obtain training data by measuring acharacteristic at a selected location in a first volume; a firstclassifier system configured to execute instructions to determine acharacteristic identification including determining a fingerprint thatincludes a model or pattern based on an analysis of the training dataincluding the measured characteristic; and a memory system to save thedetermined characteristic identification for recall and comparison to aprocedure data that includes a measured characteristic during aprocedure; wherein a training anatomical location is determined with thedetermined characteristic identification, wherein the traininganatomical location is a specific anatomical location of the firstinstrument within a subject when obtaining the training data; whereinthe characteristic is a measurement of at least one of (i) motion of thefirst instrument, (ii) fluid motion, (iii) electrical activity, (iv)pressure, or (v) tissue stiffness or density.
 2. The system of claim 1,further comprising: a second instrument configured to be positioned intoa second volume to measure the characteristic in the second volume andobtain procedure data during the procedure; a first memory system tostore the procedure data; a second classifier system to access the firstmemory system and classify the procedure data; a processor to recall thecharacteristic identification from the memory system and determine aprocedure anatomical location of the second instrument based upon acomparison of the measured procedure data to the recalled characteristicidentification; and an output device to output the procedure locationfor viewing by a user.
 3. The system of claim 2, wherein the firstvolume and the second volume are the same volume.
 4. The system of claim2, further comprising: a tracking system configured to track anavigation location of the first instrument while obtaining the trainingdata.
 5. The system of claim 2, wherein the second instrument isoperable to measure the characteristic and the second classifier systemis operable to execute a program to determine whether the obtainedprocedure data is in the determined classification.
 6. The system ofclaim 2, wherein the second instrument and the first instrument are asingle instrument.
 7. The system of claim 2, wherein a single processoris operable to execute instructions to operate as the first classifier,the second classifier, and the processor.
 8. The system of claim 1,wherein the first instrument includes an imaging system operable toacquire image data of a subject; wherein the measurement of thecharacteristic is measured with analysis of the image data.
 9. Thesystem of claim 8, wherein the imaging system is a non-invasive imagingsystem.
 10. A method of locating an instrument, comprising: a patterndetermination phase, including: acquiring a training datum by measuringa characteristic at a training location in a first volume with a firstinstrument; determining a pattern in the training datum acquired at thetraining location by executing instructions to analyze the trainingdatum of the measured characteristic; storing the determined pattern ina memory system for recall by a processor system; and a procedure phase,including: acquiring a procedure datum by measuring the characteristicduring a procedure at a procedure location in the first volume or asecond volume with a second instrument; recalling the stored determinedpattern with the processor system from the memory system during theprocedure phase; determining with the processor system whether theprocedure datum matches the pattern at least by comparing the proceduredatum to the pattern; and outputting to a user from the processor systema result of the determination of whether the procedure datum matches thepattern.
 11. The method of claim 10, wherein determining whether theprocedure datum matches the pattern at least by comparing the proceduredatum to the pattern includes determining a probability that theprocedure location is identical to the training location based upon acomparison of the procedure datum to the determined classification. 12.The method of claim 11, further comprising: outputting the determinedprobability that the procedure datum at the procedure location isidentical to the training location.
 13. The method of claim 10, whereinacquiring a training datum includes obtaining a plurality of trainingdata at the training location; wherein determining the classificationincludes extracting a fingerprint from the plurality of training data;wherein the characteristic is a measurement of at least one of (i)motion of the first instrument, (ii) fluid motion, (iii) electricalactivity, (iv) pressure, or (v) tissue stiffness or density.
 14. Themethod of 13, further comprising: determining a set of featuresconfigured to classify the procedure datum based upon the featureextracted from the training data; formulating a code based upon thedetermined set of features; and storing the code with a memory systemfor execution of the code with the processor system.
 15. The method of14, further comprising: acquiring a second training datum; and alteringthe code based upon the second training datum to increase the certaintyof a selected classification of the procedure datum; wherein measuringthe characteristic includes measuring a plurality of characteristics andthe fingerprint is based on the plurality of characteristics.
 16. Amethod of locating an instrument, comprising: recalling from a memorysystem a stored determined classification of a training datum based onmeasuring a characteristic at a training location; comparing an acquiredprocedure datum to the recalled stored determined classification byexecuting instructions, wherein the acquired procedure datum is acquiredby measuring the characteristic at a procedure location during aprocedure that occurs after the classification of the training datum;determining a probability that the procedure location is identical tothe training location at which the training datum was acquired basedupon the comparison of the procedure datum to the recalled determinedclassification; and outputting to a user the determined probability. 17.The method of claim 16, further comprising: acquiring a training datumby measuring the characteristic at the training location by measuringthe characteristic at the training location with a first instrument;determining the classification in the training datum at the traininglocation; and storing the determined classification.
 18. The method ofclaim 17, further comprising: determining the set of instructionsconfigured to classify the procedure datum based upon a featureextracted from the training datum; wherein determining the probabilitythat the procedure location is identical to the training locationincludes executing the determined set of instructions with a processor.19. The method of claim 18, wherein outputting to the user thedetermined probability includes displaying the determined probabilitywith a display device.
 20. The method of claim 16, wherein acquiring thetraining datum by measuring the characteristic at the training locationincludes a measurement of at least one of (i) motion of the firstinstrument, (ii) fluid motion, (iii) electrical activity, (iv) pressure,(v) tissue stiffness or density.